fix: harden Ext2Mgr mount assigns and Ext2Srv pipe accept

Prevent Ext2Mgr Session Manager assigns from crashing on non-EXT volumes
(MountPoints.cpp). Speed Ext2Srv named-pipe accept with dual idle
listeners, softer create retries, and no WRITE_THROUGH. Document those
changes in Ext2Mgr/IMPROVEMENTS.md and the root README. Drop the January
.gitignore entries for docs/ and Ext4Fsd.sln.

Author: Obsidian-Jackal

.gitignore

@@ -4,9 +4,3 @@ Release/
 *.vcxproj.user
 Ext2Fsd-setup.exe
 */cab/
-
-# Local docs (moved from root); keep out of version control
-docs/
-
-# Solution file can be machine-specific; remove from .gitignore to track it
-Ext4Fsd.sln

Ext2Mgr/IMPROVEMENTS.md

@@ -0,0 +1,55 @@
+# Ext2Mgr / Ext2Srv — classic stack improvements
+
+Fixes and service changes that apply to the **regular** MFC **Ext2 Volume Manager** (`Ext2Mgr/`) and/or **Ext2Srv**, independent of the Iced port.
+
+Rebuild Ext2Mgr / reinstall Ext2Srv (`Scripts\build.ps1`, `Scripts\install_driver.ps1`) to pick these up. Optional Iced GUI comparisons live on the `ext2mgr-iced` branch under `ext2mgr_iced/PORT_IMPROVEMENTS.md`.
+
+---
+
+## Ext2Mgr (`Ext2Mgr/`)
+
+### Change Drive Letters — crash on non-EXT / Session Manager
+
+**Symptom:** Choosing **Session Manager DOS Devices** (or temporary DOS devices) for an NTFS/FAT partition could crash Ext2Mgr.
+
+**Cause:** `CMountPoints::AddMountPoint` in `MountPoints.cpp`:
+
+1. On successful Session Manager registry write it called `EndDialog(0)` **without returning**, so execution continued.
+2. It always ran `Ext2QueryExt2Property(Handle, EVP)` to store Ext2Fsd automount properties.
+3. For a **partition-selected** native volume, `EVP` stayed **NULL** (only set from `m_Volume` or an EXT `m_Part->Volume` branch) → null dereference.
+
+**Fix:**
+
+- `return TRUE` immediately after a successful Session Manager assign + `EndDialog`.
+- If `EVP` is NULL, **skip** the Ext2 property IOCTL path and only assign the DOS letter (`Ext2AssignDrvLetter`), then update letter masks / notify.
+
+**Note:** Classic assign remains `DefineDosDevice` to `\Device\HarddiskVolumeN` (same path Session Manager uses). This fix is **crash safety** only.
+
+---
+
+## Ext2Srv (`Ext2Srv/`)
+
+These pipe-server changes help **both** Ext2Mgr and `ext2mgr_iced` (temporary EXT letter ops via `\\.\pipe\EXT2MGR_PSRV`).
+
+| Change | File | What |
+|--------|------|------|
+| Dual idle pipe listeners | `Ext2Pipe.cpp` (`Ext2StartPipeSrv`) | Second `Ext2PipeEngine` thread so reconnect / overlap rarely hits `ERROR_PIPE_BUSY` |
+| Soft create retries | `Ext2Pipe.cpp` (`Ext2PipeEngine`) | Cap create failures at 3×50ms (+ short sleep) instead of long backoff storms |
+| No `FILE_FLAG_WRITE_THROUGH` | `Ext2Pipe.cpp` (`Ext2CreatePipe`) | Dropped on tiny IPC messages; measured after reinstall (2026-07-28): cold connect median ~0.7 ms, burst reconnect ~0.2 ms, `QUERY_DRV` ~0.1 ms (query-only probe) |
+
+---
+
+## Intentionally not changed here
+
+| Topic | Status |
+|-------|--------|
+| Mount Manager for NTFS in classic Ext2Mgr | Not needed for Explorer when Session Manager / DosDevice targets `\Device\HarddiskVolumeN`. Classic UI still forces DosDev (`#if TRUE` in `MountPoints.cpp`). |
+| EXT-only “Assign Drive Letter” gating | Iced-only (classic still offers assign more broadly and can wait on Ext2Srv). |
+| Dead-letter detection breadth | Iced lists more orphans; classic logic unchanged. |
+
+---
+
+## Related docs
+
+- [`../README.md`](../README.md) — fork build/install scripts and driver changelog
+- `ext2mgr_iced/` on branch `ext2mgr-iced` — optional Iced GUI port

Ext2Mgr/MountPoints.cpp

@@ -123,6 +123,7 @@ CMountPoints::AddMountPoint(
         if (Ext2SetRegistryMountPoint(&drvChar, devPath, bRegistry)) {
             Ext2AssignDrvLetter(drvLetter, devPath, FALSE);
             EndDialog(0);
+            return TRUE;
         } else {
             str.Format("Failed to modify registry: SYSTEM\\CurrentControlSet\\Control\\Session Manager\\DOS Devices\n");
             AfxMessageBox(str, MB_OK|MB_ICONWARNING);
@@ -152,7 +153,42 @@ CMountPoints::AddMountPoint(
         }
     }
 
-    /* create an entry in regisgtry */
+    /* Ext2 property IOCTL — only for EXT volumes (EVP non-NULL).
+       NTFS/FAT hit this path via Change Drive Letters and used to crash
+       on Ext2QueryExt2Property(NULL). Assign the DOS letter only. */
+    if (!EVP) {
+        rc = Ext2AssignDrvLetter(drvLetter, devPath, bMountMgr);
+        if (!rc && !bMountMgr) {
+            CString str;
+            str.Format("Failed to assign new drive letter %c:\n", drvChar);
+            AfxMessageBox(str, MB_OK|MB_ICONWARNING);
+            return FALSE;
+        }
+        if (rc) {
+            m_bUpdated = TRUE;
+            if (m_Part) {
+                m_Part->DrvLetters |= letterMask;
+                if (m_Part->Volume) {
+                    m_Part->Volume->DrvLetters |= letterMask;
+                }
+                InitializeList(m_Part->DrvLetters);
+            }
+            if (m_Volume) {
+                m_Volume->DrvLetters |= letterMask;
+                InitializeList(m_Volume->DrvLetters);
+            }
+            if (m_Cdrom) {
+                m_Cdrom->DrvLetters |= letterMask;
+                InitializeList(m_Cdrom->DrvLetters);
+            }
+            m_MainDlg->SendMessage(
+                        WM_MOUNTPOINT_NOTIFY,
+                        'DA', (LPARAM)drvLetter->Letter);
+        }
+        return rc;
+    }
+
+    /* create an entry in registry (EXT only) */
     {
 
         NT::NTSTATUS status;

Ext2Srv/Ext2Pipe.cpp

@@ -151,8 +151,8 @@ Ext2CreatePipe()
 
     sa = Ext2CreateSA();
 
-    ap->p = CreateNamedPipe( _T(EXT2_MGR_SRV), PIPE_ACCESS_DUPLEX |
-                              FILE_FLAG_WRITE_THROUGH /* | ACCESS_SYSTEM_SECURITY */,
+    ap->p = CreateNamedPipe( _T(EXT2_MGR_SRV), PIPE_ACCESS_DUPLEX,
+                              /* no WRITE_THROUGH: tiny IPC messages; measure if needed */
                               PIPE_TYPE_BYTE | PIPE_READMODE_BYTE |
                               PIPE_WAIT /* PIPE_REJECT_REMOTE_CLIENTS */ ,
                               PIPE_UNLIMITED_INSTANCES,
@@ -429,21 +429,23 @@ Ext2PipeEngine(VOID *arg)
         /* create named pipe */
         ap = Ext2CreatePipe();
         if (NULL == ap) {
-            if (times++ < 10) {
-                Sleep(250 * times);
+            if (times++ < 3) {
+                Sleep(50);
                 goto retry;
             }
+            Sleep(100);
             continue;
         }
 
         /* ASSD_PIPE is valid or not */
         if (!ap->p || ap->p == INVALID_HANDLE_VALUE ||
             !ap->e || ap->e == INVALID_HANDLE_VALUE) {
             Ext2DestroyPipe(ap);
-            if (times++ < 10) {
-                Sleep(500);
+            if (times++ < 3) {
+                Sleep(50);
                 goto retry;
             }
+            Sleep(100);
             continue;
         }
 
@@ -498,6 +500,9 @@ DWORD Ext2StartPipeSrv()
         rc = WaitForSingleObject(g_wait, 1000*1);
     } while (rc == WAIT_TIMEOUT);
 
+    /* Second idle listener so a reconnect/overlap rarely hits PIPE_BUSY. */
+    _beginthread(Ext2PipeEngine, 0, NULL);
+
     return 0;
 }
 

README.md

@@ -1,3 +1,26 @@
+Scripts and building from source (this fork)
+--------------------------------------------
+
+This fork adds PowerShell scripts for building, installing, signing, and diagnosing the driver. All scripts live in **Scripts/**. Run them from the repo root, e.g. `.\Scripts\build.ps1`.
+
+**Build and install**
+- **Scripts\build.ps1** — Build driver, Ext2Srv, Ext2Mgr (requires Visual Studio 2019/2022 and WDK for the driver). Optionally signs the driver if `EXT4FSD_CERT_PATH` is set. Ext2Mgr vendors a small `Ext2Mgr/mountmgr.h`, so the manager app can be built without installing the full WDK.
+- **Scripts\install_driver.ps1** — Copy driver to System32, register kernel driver, install Ext2Srv. Run as Administrator.
+- **Scripts\uninstall_driver.ps1** — Remove driver and services.
+- **Scripts\register_driver.ps1** — Register the kernel driver service (driver must already be in System32).
+- **Scripts\disable_driver.ps1** — Disable the Ext2Fsd service (e.g. to stop boot retries after signature failures).
+
+**Signing**
+- **Scripts\sign_driver.ps1** — Sign the driver with a code-signing certificate. Set `EXT4FSD_CERT_PATH` and optionally `MSIX_CERT_PASSWORD`, or pass `-CertificatePath` / `-CertificatePassword`.
+- **Scripts\install_certificate.ps1** — Install the signing certificate into Trusted Publishers (required for loading self-signed drivers). Run as Administrator.
+
+**Diagnostics**
+- **Scripts\diagnose_ext2fsd.ps1** — Unified diagnostic (signature, cert stores, event log, driver status). Use for load failures or error 577. Use `-UseSigntool:$false` to skip signtool (e.g. when SDK is not installed).
+- **Scripts\check_driver_load_error.ps1**, **Scripts\diagnose_error_577.ps1**, **Scripts\verify_driver_signature.ps1** — Wrappers that call `diagnose_ext2fsd.ps1`.
+
+**Other**
+- **Scripts\fix_sdk_version.ps1** — Update project files' `WindowsTargetPlatformVersion` to match the installed SDK.
+
 
 Latest release
 --------------
@@ -50,6 +73,16 @@ Changes to the source code in git after latest release
     - The fields s_wtime and s_wtime_hi in the superblock will be
       updated with the current time at shutdown.
 
+    - Timeouts on block/PnP/fsctl waits so surprise-removal of USB
+      or other removable ext4 volumes no longer hangs the system
+      waiting forever for I/O that will never complete.
+
+    - Corrected the wait argument to CcCopyRead / CcCopyWrite and
+      simplified the related read/write paths.
+
+    - Filesystems with EXT4_FEATURE_INCOMPAT_CASEFOLD can be mounted
+      (the feature bit is treated as supported).
+
     Application:
 
     - If an on disk filesystem contains new ext4 features that is
@@ -66,6 +99,16 @@ Changes to the source code in git after latest release
     - The donate dialog box is disabled because the information in
       it is outdated.
 
+    - High-DPI awareness is disabled in the Ext2Mgr project so the
+      classic Win32 UI scales more predictably on high-resolution
+      monitors.
+
+    - Ext2Mgr includes a subset of mountmgr.h so the application can
+      be compiled without installing the Windows Driver Kit.
+
+    - Fork manager notes (this tree): Ext2Mgr/IMPROVEMENTS.md covers
+      classic Ext2Mgr crash fixes and Ext2Srv pipe speedups.
+
 
 About
 -----
@@ -172,5 +215,9 @@ Unsupported Ext4 Features
     2, EXT4_FEATURE_INCOMPAT_MMP (multiple mount protection)
     3, EXT4_FEATURE_INCOMPAT_INLINE_DATA (storing small files in inode)
     4, EXT4_FEATURE_INCOMPAT_ENCRYPT
-    5, EXT4_FEATURE_INCOMPAT_CASEFOLD (case insensitive file names (claimed to be used by SteamOS as default))
-    6, EXT4_FEATURE_INCOMPAT_LARGEDIR (3-level htree)
+    5, EXT4_FEATURE_INCOMPAT_LARGEDIR (3-level htree)
+
+    Note: EXT4_FEATURE_INCOMPAT_CASEFOLD is no longer in this list;
+    the driver accepts that incompat bit so casefolded volumes can
+    be mounted. Full case-insensitive name matching semantics may
+    still be incomplete compared to Linux.